import React, { Component } from 'react';

class Demo extends Component{
  render(){
    return <div>
      <h1>Demo 组件</h1>
    </div>
  }
}
class App extends Component {
  render() {
    return (
      <div>
        <Demo>123</Demo>
      </div>
    );
  }
}

export default App;
